4 Calibration
30
4.5
TURB (turbidity) Span Calibration
Only the span calibration is applied to the calibration method for TURB.
Perform TURB span calibration after performing the common zero calibration and the
common span calibration of UV/VIS.
Refer to "4.1 Calibration Pattern and its Cycle" (page 15).
TURB span calibration is to obtain the turbidity coefficient converted from the light absorption
of VIS.
The rough standard of the TURB measuring range is approximately 200 mg/L by kaolin
concentration.
4.5.1
How to Prepare the Calibration Solution
<Reference> How to Prepare the TURB Span Calibration Solution
Polystyrene latex standard solution (100 degrees)
After shaking up the commercially available turbidity standard solution of polystyrene latex
(1000 degrees), immediately take the 200 mL. And pour into the 2000 mL measuring flask,
and add the tap water to the gauge line.
Tip
If using the calibration solution just after compounding it, air bubbles may affect the readings. Stable
calibration requires some time after compounding.
Kaolin standard solution
Refer to JIS-K101.
Purified kaolin
Put approximately 10 g of kaolin clay into the 500 mL beaker, add the 300 mL of water and 0.2
g of sodium diphosphate decahydrate designated by JIS-K8785, and stir hard using the
magnetic stirrer for approximately 3 minutes. Pour the solution into the 1000 mL measuring
cylinder (lid is available), add the water to the 1000 mL gauge line, put on the lid, and stir hard
for approximately 1 minute. After leaving the solution at rest for 1 hour in ambient temperature,
discard 250 mL of the solution from the top using a siphon, and obtain another 250 mL of
solution.
Centrifuge the solution in 3000 min
-1
(adjusting the rotating speed according to the semi
diameter of the rotary part of the centrifugal separator) for 20 minutes, or filter using a filter
with a pore diameter of under 1
m.
Heat the filtered kaolin at a temperature of 105°C to 110°C for approximately 3 hours, stand to
cool in the desiccators, and keep the solution in a wide-mouth bottle.
Concentrated kaolin standard solution (1000 mg/L)
Take 1.00 g of the purified kaolin to disperse in a moderate amount of water, and pour the full
dosage of kaolin standard solution into the 1000 mL flask. Then, after adding approximately
800 mL of pure water and approximately 10 mL of formaldehyde designated by JIS-K8872,
add pure water up to the gauge line.
JIS
Sample
Quantity
-
Kaolin clay
Approximately 10 g
JIS-K8785
Sodium diphosphate decahydrate 0.2 g
JIS-K8872
Formaldehyde
Approximately 10 mL
